An internal combustion engine may include adjustable intake and/or adjustable exhaust camshafts. The adjustability of the intake camshafts and exhaust camshafts provides opportunities to improve engine performance, emissions, and fuel economy. However, if camshafts are not positioned properly, the benefits of variable valve timing may not be fully realized. Manufacturing variation of camshafts and camshaft actuators may result in camshaft positioning errors. Further, installation of camshafts and camshaft actuators in an engine may result in camshaft positioning errors. If an engine controller is programmed with desired camshaft positions based on operation of a development engine, and if camshafts and camshaft actuators of a production engine are positioned differently than the camshafts and camshaft actuators of the development engine when commanded to a same position, then performance, emissions, and fuel economy of the production engine may degrade. Therefore, it would be desirable to provide a way of correcting intake camshaft and exhaust camshaft positioning errors.
The inventors herein have recognized the above-mentioned issues and have developed an engine operating method, comprising: adjusting a first camshaft position of a first engine via a controller in response to an error between a predetermined camshaft position of a second engine and a second camshaft position of the first engine; and moving a camshaft of the first engine to the adjusted first camshaft position via the controller.
By adjusting a first camshaft position of a first engine in response to an error between a predetermined camshaft position of a second engine and a second camshaft position of the first engine, it may be possible to provide the technical result of adjusting camshaft timing of the first engine to match camshaft timing of the second engine so that performance, emissions, and fuel economy of the first engine more closely matches performance, emissions, and fuel economy of the second engine. For example, camshaft timings that provide desired performance, emissions, and fuel economy for the second engine may be stored in memory of a controller of the first engine. The camshaft timings stored in memory may be adjusted based on a camshaft angle where the intake manifold pressure of the first engine is a minimum. The camshaft angle where intake manifold pressure for the first engine is a minimum is compared to a camshaft angle where intake manifold pressure for the second engine is a minimum. The camshaft timings stored in memory are adjusted based on the comparison. In this way, camshaft timing of one engine may be matched to camshaft timing of a different engine even when some manufacturing variation is present in the engine system.
The present description may provide several advantages. For example, the approach may improve vehicle performance, fuel economy, and emissions. Further, the approach may reduce performance, fuel economy, and emissions variation within a group of vehicles. Further still, the approach may be performed in a vehicle on a road or within a manufacturing or testing facility.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.